21123355103 has 4 divisors (see below), whose sum is σ = 21638558928. Its totient is φ = 20608151280.

The previous prime is 21123355073. The next prime is 21123355129. The reversal of 21123355103 is 30155332112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21123355103 - 2¹⁰ = 21123354079 is a prime.

It is a super-2 number, since 2×21123355103² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123355133) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 257601851 + ... + 257601932.

It is an arithmetic number, because the mean of its divisors is an integer number (5409639732).

Almost surely, 2^21123355103 is an apocalyptic number.

21123355103 is a deficient number, since it is larger than the sum of its proper divisors (515203825).

21123355103 is an equidigital number, since it uses as much as digits as its factorization.

21123355103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515203824.

The product of its (nonzero) digits is 2700, while the sum is 26.

Adding to 21123355103 its reverse (30155332112), we get a palindrome (51278687215).

The spelling of 21123355103 in words is "twenty-one billion, one hundred twenty-three million, three hundred fifty-five thousand, one hundred three".